1. Field of the Invention
The valve assembly of the present invention has particular application as a closure device for use inside of an enclosed container as, for example, a waste receptacle in aircraft.
2. Description of the Prior Art
The prior art valve assemblies used in waste receptacles have been supported from the top of the receptacle and extend axially for some distance to engage a valve seat in the bottom of the receptacle. One prior art approach controlled the axial alignment of the valve plug with the valve seat by telescoping tubes. The valve plug was inserted into and held in the valve seat by a helically coiled spring which was enclosed by the telescoping tubes and was compressed between the valve plug and the support structure.
In the construction of the waste receptacle, in the installation of the valve assembly, and in the operation of the valve assembly, errors in axial alignment of the valve plug and valve seat have been encountered. In such prior art valve assemblies, when an error in axial alignment was introduced into the system, the valve plug would hang up on the valve seat and leave an opening through which the contents of the receptacle could pass.
When the prior art valves in the aircraft waste receptacle leaked, the contents of the receptacle escaped, creating a difficult and distasteful clean-up job for the aircraft maintenance personnel. In some instances, the leakage has presented a danger to the operation of the aircraft due to the formation of ice.
An alternative, prior art approach has been proposed in U.S. Pat. No. 4,017,913, to Judd. A spherical joint was included between the tapered valve plug and the telescoping alignment tubes, positioning the center of rotation of such joint on the outlet side of the tapered valve seat. This arrangement also positioned the spherical contact surface of such point (e.g., the locus of application of the compressive spring force on the valve plug) on the outlet side of the valve seat when the valve plug has engaged the valve seat.
When the valve plug was misaligned axially with the valve seat and encountered the lip of the valve seat, the spherical joint permitted the valve plug to rotate into the seat and slide into engagement with the valve seat. However, this approach required a complex mechanical assembly and was of limited utility when the drain was eccentric relative to the axis between the drain opening and the acuating mechanisms.